When logged is as a user in print-ads group I get the ModelAdmin for the object. The gridfield displays the object and the add button. The odd thing is the print-ad group can add a DataObject with the button (which it shouldn't) and it is unable to click on individual dataobjects in the gridfield to view teh details.

I have started to use the 'implements PermissionProvider' method for dealing with permissions, then it's just a case of ticking the required boxes in the security group permissions page. example below, hope this helps.

I know what you mean, it was a real eureka moment for me when I finally got it. The main thing is the implementation of the permission provider, then you create the permission types, and finally you create functions for those created permissions then you can use